A check or guard rail is provided extending parallel to a running rail at a sharp curve or railroad switch to prevent a rail-car wheel from slipping sideways off the running rail. In particular they are used at the frog of a rail system with a UIC 33 or U69 profile. Such guard rails are secured to guide-rail anchor plates and must extend parallel to and at an exact spacing from the running rail. They are subject to considerable wear.
As a rule such a guide rail is through-bolted to the guide-rail anchor plate. To this end the anchor plates must be installed on the sleepers at an exact spacing so that their holes correspond exactly to the holes in the preformed guide rails. Obviously installing the anchor plates this precisely in the field is fairly difficult and often requires that the anchor plates be removed and reinstalled, greatly slowing the installation process.
It is also known to simply drill the anchor plates and/or the guide rail at the site to ensure that their holes align perfectly. Such a procedure is also fairly cumbersome and difficult to carry out in the field. This is particularly disadvantageous when guide rails are being replaced, as the rail stretch must be taken out of service for a considerable time while the new guide rails are fitted, drilled, and mounted.